Pertussis | Whooping Cough | Clinical | Disease Specifics | CDC Disease Specifics Reference Pertussis is an acute infectious disease caused by the bacterium Bordetella pertussis. In the 20th century, pertussis was one of the most common childhood diseases and a major cause of childhood mortality in the United States. Before the availability of pertussis vaccine in the 1940s, more than 200,000 cases of pertussis were reported annually. Since widespread use of the vaccine began, incidence has decreased more than 75% compared with the pre-vaccine era. However, since the 1980s there's been an increase in the number of reported cases of pertussis. In 2012, the last peak year, 48,277 cases of pertussis were reported. However, CDC believes that much of the disease goes unrecognized and unreported.

Several factors have likely contributed to the increase in reported cases, including increased awareness and improved recognition of pertussis among clinicians; greater access to and use of laboratory diagnostics, especially polymerase chain reaction (PCR) testing; increased surveillance and reporting of pertussis to public health departments; and waning immunity from vaccines. Additionally, Bordetella pertussis are also always changing at a genetic level. Research is underway to determine if any of the recent changes may be related to the increase in disease. Bordetella pertussis B. pertussis is a fastidious, gram-negative bacterium requiring special media for isolation. B. pertussis produces multiple antigenic and biologically active products including: Gram stain of Bordetella pertussis Pertussis toxin Pertactin Tracheal cytotoxin These products are responsible for the clinical features of pertussis and an immune response to one or more produces immunity following infection. Some observational studies suggest that pertussis infection can provide immunity for 4 to 20 years. Pathogenesis Pertussis is primarily a toxin-mediated disease.

The bacteria attach to the cilia of the respiratory epithelial cells, produce toxins that paralyze the cilia, and cause inflammation of the respiratory tract, which interferes with the clearing of pulmonary secretions. Until recently, it was thought that B. pertussis did not invade the tissues; however, recent studies have suggested that the bacteria are present in alveolar macrophages. Reference Pertussis | Whooping Cough | Signs and Symptoms | CDC Signs and Symptoms Pertussis (whooping cough) can cause serious illness in babies, children, teens, and adults. Symptoms of pertussis usually develop within 5 to 10 days after being exposed, but sometimes not for as long as 3 weeks. Early Symptoms In those who have been vaccinated: In most cases, the cough won’t last as many days Coughing fits, whooping, and vomiting after coughing fits occur less often The percentage of children with apnea (long pause in breathing), cyanosis (blue/purplish skin coloration due to lack of oxygen) and vomiting is less The disease usually starts with cold-like symptoms and maybe a mild cough or fever. In babies, the cough can be minimal or not even there.

Babies may have a symptom known as "apnea." Apnea is a pause in the child's breathing pattern. Pertussis is most dangerous for babies. About half of babies younger than 1 year who get the disease need care in the hospital. Learn more about pertussis complications . Early symptoms can last for 1 to 2 weeks and usually include: Runny nose Low-grade fever (generally minimal throughout the course of the disease) Mild, occasional cough Apnea – a pause in breathing (in babies) Because pertussis in its early stages appears to be nothing more than the common cold, it is often not suspected or diagnosed until the more severe symptoms appear. Top of Page Pertussis in Babies It is important to know that many babies with pertussis don’t cough at all. Instead it causes them to stop breathing and turn blue.

Later-stage Symptoms After 1 to 2 weeks and as the disease progresses, the traditional symptoms of pertussis may appear and include: Paroxysms (fits) of many, rapid coughs followed by a high-pitched "whoop" Vomiting (throwing up) during or after coughing fits Exhaustion (very tired) after coughing fits Pertussis can cause violent and rapid coughing, over and over, until the air is gone from the lungs and you are forced to inhale with a loud "whooping" sound. This extreme coughing can cause you to throw up and be very tired. Although you are often exhausted after a coughing fit, you usually appear fairly well in-between. Coughing fits generally become more common and bad as the illness continues, and can occur more often at night. The coughing fits can go on for up to 10 weeks or more. In China, pertussis is known as the "100 day cough." However, the "whoop" is often not there for people who have milder (less serious) disease. The infection is generally milder in teens and adults, especially those who have been vaccinated.

Whooping Cough - HealthyChildren.org Whooping Cough Article Body What is whooping cough? Pertussis, or whooping cough, is less common in young children than it used to be, as the pertussis vaccine has made most children immune. Before this vaccine was developed, there were several hundred thousand cases of whooping cough each year in the United States. Now there are approximately 1 million cases a year in the US, but these are mostly in adults and adolescents . This illness is caused by pertussis bacteria, which attack the lining of the breathing passages (bronchi and bronchioles), producing severe inflammation and narrowing of the airways. Severe coughing is a prominent symptom. If not recognized properly, the bacteria may spread to those in close contact with the infected person, through her respiratory secretions. Who is at risk? Infants under one year of age are at greatest risk of developing severe breathing problems and life- threatening illness from whooping cough. Because the child is short of breath, she inhales deeply and quickly between coughs. These breaths (particularly in older infants) frequently make a "whooping" sound—which is how this illness got its common name.

The intense coughing scatters the pertussis bacteria into the air, spreading the disease to other susceptible persons. Symptoms Pertussis often acts like a common cold for a week or two. Then the cough gets worse, and the older child may start to have the characteristic "whoop"s. During this phase (which can last two weeks or more), the child often is short of breath and can look bluish around the mouth. She also may tear, drool, and vomit. Infants with pertussis become exhausted and develop complications such as susceptibility to other infections, pneumonia , and seizures . Pertussis can be fatal in some infants, but the usual course is for recovery to begin after two to four more weeks. The cough may not disappear for months, and may return with subsequent respiratory infections. When to call the doctor Pertussis infection starts out acting like a cold. You should consider the possibility of whooping cough if the following conditions are present. The child is a very young infant who has not been fully immunized and/or has had exposure to someone with a chronic cough or the disease. The child's cough becomes more severe and frequent, or her lips and fingertips become dark or blue.

She becomes exhausted after coughing episodes, eats poorly, vomits after coughing, and/or looks "sick." When your child needs hospital care The majority of infants with whooping cough who are less than six months old, and slightly less than one-half of older babies with the disease, initially are treated in the hospital. This more intensive care can decrease the chances of complications. These complications can include pneumonia, which occurs in slightly less than one fourth of children under one year old who have whooping cough. (If your child is older, she is more likely to be treated only at home.) While in the hospital, your child may need to have the thick respiratory secretions suctioned. His breathing will be monitored, and he may need to have oxygen administered. For several days, your youngster will be isolated from other patients to keep the infection from spreading to them. Treatment Whooping cough is treated with antibiotics, usually for two weeks. These medications are most effective when they are given in the first stage of the illness before coughing spells begin. Although antibiotics can stop the spread of the whooping cough infection, they cannot prevent or treat the cough itself.

Because cough medicines do not relieve the coughing spells, your pediatrician probably will recommend other forms of home treatment to help manage the cough. Let your child rest in bed and use a cool-mist vaporizer to help soothe his irritated lungs and breathing passages. A vaporizer also will help loosen secretions in the respiratory tract. Ask your pediatrician for instructions on the best position for your child to help drain those secretions and improve breathing. Also ask your doctor whether antibiotics or vaccine boosters need to be given to others in your household to prevent them from developing the disease. Prevention The best way to protect your child against pertussis is with DTaP vaccination (immunizations at two months, four months, and six months of age, and booster shots at twelve to eighteen months and at four or five years of age). See Recommended Immunization Schedules . Tdap also protects against pertussis. A single dose of Tdap vaccine should be administered to children 7 through 10 years of age who were underimmunized with DTaP or who have an incomplete vaccine history. The American Academy of Pediatrics (AAP) continues to recommend vaccination of adolescents, including pregnant adolescents . Pregnant women should also receive the vaccine.

A single dose should be given to adults who have contact with infants, even if they are older than 65, and for health care workers of any age. Last Updated 11/21/2015 Source Adapted from Caring for Your Baby and Young Child: Birth to Age Five (Copyright © 2009 American Academy of Pediatrics) The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances. Whooping Cough (Pertussis): Treatment and Prevention What is whooping cough ? Whooping cough is a bacterial infection that's highly contagious, and it's also vaccine preventable. Especially in young kids and unvaccinated people, it causes a severe cough , which is the reason for the name, "whooping cough." What kind of infection causes whooping cough ? It's caused by bacteria called Bordetella pertussis. What are the symptoms of whooping cough? It starts like a cold, with congestion and upper respiratory symptoms, and then progresses to a cough.

You have fits of coughing that are so severe that you can't stop or catch your breath. It's that severe, prolonged cough, and especially the characteristic paroxysms [uncontrolled fits] of cough that trigger physicians to be worried about pertussis and try to confirm the diagnosis. The symptoms are pretty nonspecific, and so doctors don't always suspect it. Pertussis is high on the list if that whoop is present. The “whoop” sounds like a sharp gasping intake of breath after all the air has been coughed out of your lungs . If it's not, it's likely to go unrecognized because there aren't really other signs and symptoms that are as characteristic. How does whooping cough spread from person to person? It spreads through close contact with oral secretions or respiratory droplets. So it's easily spread through the cough, especially when people are in close contact, like living in the same house with a person who has whooping cough. It can also be spread through sneezes - anything that spreads respiratory secretions. Who is most at risk for whooping cough? The highest incidence is in infants, and they're also at greatest risk for complications if they develop the disease.

In fact, the great majority of fatal cases in the country each year are in infants less than 6 months of age, especially if they're too young to have received their first vaccination. How is whooping cough treated? It's a bacterial infection, so it can be treated with antibiotics , usually erythromycin or a family of antibiotics like erythromycin. Erythromycin is taken for 2 weeks. Continued If antibiotics are recommended, they should take all the doses and finish the recommended course. It's important for a couple of reasons. If the child's doctor feels that antibiotics are necessary, it's important to take the doses on time to develop and maintain the appropriate antibiotic levels in the blood to clear the infection. And missing a dose or stopping early can sometimes result in a relapse. It's also important in general, because one of the things that promotes antibiotic resistance in bacteria is stopping and starting [antibiotics]. Over-the-counter cough medicines are not recommended and don't really help. The prescription medicines that are really effective for cough are pretty strong medicines, so they're generally avoided in young children and probably not effective in pertussis specifically. It's commonly recommended to minimize the things that can trigger the cough.

A humidifier helps. Breathing moist air will help. With younger kids, try to keep them calm and not agitated or running around. Infants or people with severe disease sometimes require ... hospitalization, sometimes in intensive care. It can be serious enough to require intubation and ventilation -- in which a breathing tube is inserted into the throat, both to protect the airways and to assist with breathing until they can recover from the infection. What health problems can whooping cough cause in infants? Concerning things include pneumonias. Because the cough is so severe, blood vessels can break because of the pressure generated from coughing . That causes bleeding inside the brain , which can be very serious. In infants [whooping cough] can be life threatening. How can I prevent my baby from getting whooping cough? Whooping cough is commonly thought of as sort of an old-time disease of childhood that went away with vaccination, but it never really went away. So it's important that we maintain high vaccination coverage in kids. It's also a disease that adolescents and adults can get. The best way to prevent it is to get vaccinated. For kids, vaccinations start at 2 months.

They get the pertussis vaccination with diphtheria and tetanus . And then doses at 4 months and 6 months. Then there's a booster at 15 to 18 months, and another booster at 4 to 6 years before they start school. Continued The Tdap vaccine is recommended for all adolescents, preferably at age 11 or 12 during a preventive care visit with their doctor. But anyone who hasn't gotten it at age 11 or 12 can get a dose. If adults have never had [the vaccine], they should definitely get it, and they can get it at any time. They don't have to wait until they're due for their tetanus vaccine . For infants who are too young to be vaccinated and who are at highest risk for disease and severe complications, we recommend that everybody who is in the house or caring for the baby get vaccinated to help protect the baby. How do outbreaks of whooping cough start? Things that can promote outbreaks or promote the spread of disease include low vaccination coverage. Protection from the vaccine doesn't last forever. Immunity wanes over time. That's why you commonly see outbreaks in teenagers.

The reason that the adolescent and adult Tdap booster was developed was really the increase in disease observed in teenagers and young adults as a result of waning immunity. Are we seeing more outbreaks of whooping cough, and if so, why? It definitely comes and goes. There are frequently outbreaks. But most are kind of small clusters of dozens of cases. Large, community-wide outbreaks are pretty rare. Occasionally, every 3 to 5 years, we see big increases in states or regions of the country. Transmission is a definite and recognized cycle. It's thought that as transmission declines, the number of people in the total population who are susceptible gradually increases because the disease isn't circulating as much, and protection from the vaccine wanes over time. And then transmission gradually increases and runs through the susceptible population until it starts to decline again. Do other family members need to take preventive antibiotics or vaccine boosters if they've been exposed? They do. It's always important to make sure that kids are up-to-date with their immunizations . With the Tdap booster, make sure adolescents and adults are up-to-date with their immunizations . The person with pertussis should be treated, and people who are in close contact should get preventive antibiotics.

What Is Whooping Cough and How Can You Prevent It? Updated March 22, 2016 What Is Pertussis (Whooping Cough)? Pertussis, or whooping cough, is a bacterial infection that causes a person to have severe coughing fits. The cough can be so bad that it may cause the person to choke or vomit. The name “whooping cough” comes from the sound that is made when a breath is taken after a coughing spell. What Are the Symptoms? Pertussis usually begins with symptoms similar to those of a common cold , such as runny nose, congestion, sneezing, watery eyes and mild fevers. Unlike the common cold which typically lasts a week to 10 days, these symptoms will last for about two weeks in individuals with pertussis who have not been vaccinated. These symptoms may not last as long in people who have been vaccinated. Next, a dry hacking cough will start and will progress to prolonged coughing spasms. These coughing spasms can be so violent that it is difficult for the person to catch their breath and vomiting may occur.

Coughing spells are often followed by a loud “whoop” noise made when the person finally catches their breath. Typically, this stage lasts anywhere between 2 to 6 weeks. Potential complications of pertussis include pneumonia, emphysema, weight loss (due to poor feeding), vomiting, bleeding in the brain (cerebral hemorrhage), seizures and -- rarely -- infection of the lining of the brain (encephalitis). How Does it Affect Children? Pertussis is most severe in infants, especially those under three months of age. Children under 3 months who have pertussis will be hospitalized and many between 3 to 6 months will be hospitalized as well. In young infants, the “whooping” sound may not be as obvious or may not be heard at all. However, the disease is more serious in young children because the child can actually suffocate from the coughing fits. Other complications in infants include seizures, ear infections and pneumonia. How Is Pertussis Treated? Because pertussis is a bacterial infection, it is treated with antibiotics. It is also highly contagious and family members of those with a confirmed case of pertussis may be treated with antibiotics as well.

Anyone diagnosed with pertussis should be isolated for five days after starting antibiotics and exposure to infants younger than 3 months should be avoided. Pertussis was once prevalent in the United States and was one of the leading causes of death among young children. However, due to good immunization practices, it is now rare. Unfortunately, cases of pertussis are on the rise once again. It is thought that the immunizations given during childhood may not provide immunity for longer than 10 years, so new recommendations about adults receiving a booster vaccine have been added. Whooping Cough | Pertussis | Whooping Cough Symptoms | MedlinePlus Patient Handouts Summary Whooping cough is an infectious bacterial disease that causes uncontrollable coughing. The name comes from the noise you make when you take a breath after you cough. You may have choking spells or may cough so hard that you vomit. Anyone can get whooping cough, but it is more common in infants and children. It's especially dangerous for infants. The coughing spells can be so bad that it is hard for infants to eat, drink, or breathe. To make a diagnosis, your doctor may do a physical exam, blood tests, chest x-rays, or nose or throat cultures.

Before there was a vaccine, whooping cough was one of the most common childhood diseases and a major cause of childhood deaths in the U.S. Now most cases are prevented by vaccines . If you have whooping cough, treatment with antibiotics may help if given early. Centers for Disease Control and Prevention Start Here Pertussis Pertussis Important It is possible that the main title of the report Pertussis is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report. Synonyms None General Discussion Pertussis is a highly contagious acute respiratory disease caused by the bacteria Bordetella pertussis. This disease has 3 stages: catarrhal, paroxysmal, and convalescent. The symptoms of the catarrhal stage are mild and may go unnoticed. The paroxysmal stage of Pertussis is characterized by episodes of coughing with a distinctive "whooping" sound when breathing in (inspiration). This characteristic cough gives the disease its common name, Whooping Cough. During the convalescent stage, episodes of coughing are less frequent and symptoms improve.

The incidence of Pertussis has diminished greatly with widespread use of the DPT vaccine (Diphtheria Pertussis Tetanus ), but in certain areas of the United States outbreaks have occurred periodically in recent years. Resources Centers for Disease Control and Prevention 1600 Clifton Road NE NIH/National Institute of Allergy and Infectious Diseases Office of Communications and Government Relations 6610 Rockledge Drive, MSC 6612 Bethesda, MD 20892-6612 NIH/National Institute of Child Health and Human Development 31 Center Dr Genetic and Rare Diseases (GARD) Information Center PO Box 8126 Internet: For a Complete Report This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information". The information provided in this report is not intended for diagnostic purposes.

It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians. It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder. For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O.

Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email orphan@rarediseases.org Last Updated: 4/10/2009 Whooping Cough (Pertussis) Whooping Cough (Pertussis) La tos ferina Whooping cough (pertussis) is an infection of the respiratory system caused by the bacterium Bordetella pertussis (or B. pertussis). It mainly affects babies younger than 6 months old who aren't yet protected by immunizations, and kids 11 to 18 years old whose immunity has started to fade. Whooping cough causes severe coughing spells, which can sometimes end in a "whooping" sound when the child breathes in. Before a vaccine was available, pertussis killed about 9,000 people in the United States each year. Now, the pertussis vaccine has reduced the annual number of deaths to less than 20. But in recent years, the number of cases has started to rise.

In 2012, the number of whooping cough cases spiked up to almost 50,000, the highest level since the 1950s. Signs & Symptoms The first symptoms of whooping cough are similar to those of a common cold: runny nose mild cough low-grade fever After about 1 to 2 weeks, the dry, irritating cough evolves into coughing spells. During a coughing spell, which can last for more than a minute, a child may turn red or purple. At the end of a spell, the child may make the characteristic whooping sound when breathing in or may vomit. Between spells, the child usually feels well. While many infants and younger kids with whooping cough develop the coughing fits and accompanying whoop, not all do. And sometimes babies don't cough or whoop as older kids do. Infants may look as if they're gasping for air with a reddened face and may actually stop breathing (this is called apnea) for a few seconds during very bad spells. Adults and teens may have milder or different symptoms, such as a prolonged cough (rather than coughing spells) or coughing without the whoop.

continue Contagiousness Pertussis is highly contagious. The bacteria spread from person to person through tiny drops of fluid from an infected person's nose or mouth. These may become airborne when the person sneezes, coughs, or laughs. Others then can become infected by inhaling the drops or getting the drops on their hands and then touching their mouths or noses. Infected people are most contagious during the earliest stages of the illness for up to about 2 weeks after the cough begins. Antibiotics shorten the period of contagiousness to 5 days following the start of antibiotic treatment. Prevention Whooping cough can be prevented with the pertussis vaccine , which is part of the DTaP (diphtheria, tetanus, acellular pertussis) immunization . DTaP immunizations are routinely given in five doses before a child's sixth birthday. For additional protection in case immunity fades, experts recommend that kids ages 11-18 get a booster shot of the new combination vaccine (called Tdap), ideally when they're 11 or 12 years old. The Tdap vaccine is similar to DTaP but with lower concentrations of diphtheria and tetanus toxoid.

It also should be given to adults who did not receive it as preteens or teens. The vaccine is also recommended for all pregnant women during the second half of each pregnancy, regardless of whether or not they had the vaccine before, or when it was last given. Getting the vaccine is especially important for people who are in close contact with infants, because babies can develop severe and potentially life-threatening complications from whooping cough. An adult's immunity to whooping cough lessens over time, so getting vaccinated and protecting yourself against the infection also helps protect your infant or child from getting it. As is the case with all immunization schedules, there are important exceptions and special circumstances. Your doctor will have the most current information. People who live with or come into close contact with someone who has pertussis should receive antibiotics to prevent the spread of the disease, even if they've already been vaccinated against it. Young kids who have not received all five doses of the vaccine may need a booster dose if exposed to an infected family member. Incubation The incubation period (the time between infection and the start of symptoms) for whooping cough is usually 7 to 10 days, but can be as long as 21 days.

previous continue Duration Pertussis usually causes prolonged symptoms — 1 to 2 weeks of common cold symptoms, followed by up to 3 months of severe coughing. The last stage consists of another few weeks of recovery with gradual clearing of symptoms. In some children, the recovery period can last for months. Treatment Call the doctor if you suspect that your child has whooping cough. To make a diagnosis, the doctor will take a medical history, do a thorough physical exam, and may take nose and throat mucus samples to be checked in a lab. Blood tests and a chest X-ray also might be done. Whooping cough is treated with antibiotics. Many experts believe that antibiotics are most effective in shortening the length of the infection when they're given in the first stage of the illness, before coughing spells begin. But even if antibiotics are started later, they're still important because they can stop the spread of the pertussis infection to others. Ask your doctor whether preventive antibiotics or vaccine boosters for other family members are needed. Some kids with whooping cough need to be treated in a hospital. Babies and younger children are more likely to be hospitalized because they're at greater risk for problems like pneumonia .

Whooping cough can be life-threatening for infants younger than 6 months, so they almost always need hospital treatment. Other potential complications include difficulty breathing, periods of apnea, needing oxygen (particularly during a coughing spell), and dehydration . While in the hospital, a child may need suctioning to clear the airways. Breathing will be watched closely, and oxygen given if needed. Intravenous (IV) fluids might be needed if a child shows signs of dehydration or has difficulty eating. Precautions will be taken to prevent the infection from spreading to other patients, hospital staff, and visitors. previous continue Home Care If your child is being treated for pertussis at home, follow the schedule for giving antibiotics exactly as your doctor prescribed. Giving cough medicine probably will not help, as even the strongest usually can't relieve the coughing spells of whooping cough. The cough is actually the body's way of trying to clear the airways. (Due to potential side effects, cough medicines are never recommended for children under age 6.) During recovery, let your child rest in bed and use a cool-mist vaporizer to help soothe irritated lungs and breathing passages.

(Be sure to follow directions for keeping it clean and mold-free.) And keep your home free of irritants that can trigger coughing spells, such as aerosol sprays; tobacco smoke; and smoke from cooking, fireplaces, and wood-burning stoves. Kids with whooping cough may vomit or not eat or drink much because of the coughing. So offer smaller, more frequent meals and encourage your child to drink lots of fluids. Watch for signs of dehydration, including thirst, irritability, restlessness, lethargy, sunken eyes, a dry mouth and tongue, dry skin, crying without tears, and fewer trips to the bathroom to pee (or in infants, fewer wet diapers). When to Call the Doctor Call the doctor if you think that your child has whooping cough or has been exposed to someone with whooping cough, even if your child has already had all scheduled pertussis immunizations.

This is especially important if your child has long coughing spells and: the coughing make your child's skin or lips turn red, purple, or blue your child vomits after coughing there's a whooping sound after the cough your child has trouble breathing or seems to have brief periods of not breathing (apnea) your child seems very sluggish If your child has been diagnosed with whooping cough and is being treated at home, get immediate medical care if he or she develops difficulty breathing or shows signs of dehydration. NOVA - Official Website | Why is Whooping Cough Back? NOVA Why is Whooping Cough Back? By Emily Willingham and Laura Helft Posted 09.05.14 NOVA Of all immunizations against infectious diseases, the vaccine against whooping cough probably has the most complicated history and the most unpredictable future. Why does whooping cough, also known as pertussis, present such a tough public-health problem? What is whooping cough? Bordetella pertussis bacteria cause whooping cough by sticking to the cells lining the lungs and producing a toxin that blocks lung function.

The main symptom of pertussis is a gasping cough characterized by a whooping sound that gives the disease its common name. The cough can be intense enough to cause vomiting or break ribs. Although adults and older children usually survive the disease—while enduring considerable discomfort—it can be fatal in infants, the age group with the highest pertussis death rate. Antibiotics can cure the disease if the infection is identified early enough, but there is no treatment that can neutralize the pertussis toxin once it's present in the lungs. An infected person first shows symptoms of a common cold, including sniffles and a low-grade fever; but once the characteristic cough develops, it can last for weeks. One nickname for pertussis is the " 100-day cough ." An infant with pertussis is given an oxygen mask. Enlarge Photo credit: © WGBH Educational Foundation Pertussis kills about 300,000 people each year worldwide, most of them infants. According to the U.S. Centers for Disease Control and Prevention (CDC), infants under one year old not only are at greatest risk of death from the disease, but they also have the highest reported rate of pertussis.

Even in older children, the consequences of the disease can be serious; one in 20 children who contract pertussis has nervous system damage. The disease, which passes from person to person through the air, is highly contagious; one infected person can spread the disease to more than a dozen other people. An infected person is contagious even when symptoms are indistinguishable from those of a cold, before the "whooping" cough begins. In the United States, pertussis affected more than 200,000 people a year in the late 1930s and early 1940s. The advent of a vaccine against the disease in the 1940s led to a drop in those numbers, to a low point of just over 1,000 cases in 1976. Then, in the 1990s, the numbers started rising again . Pertussis cases in the United States, 1950-2013 Enlarge Photo credit: © Tangled Bank Studios; source data from Centers for Disease Control Is there a resurgence of pertussis?

By the first decade of the 21st century, pertussis outbreaks had started to increase in number and size. California has been slammed with two major outbreaks: one in 2010 that hit 9,120 people and left 10 infants dead, and one in 2014 that as of August involved 7,503 cases and three infant deaths . Whooping cough cases have always waxed and waned in natural cycles, peaking every three to five years. Since the 1990s, though, the number of cases has been on a steady climb . Doctors are recognizing the disease earlier and more often, now that it's back on their radars, and testing for it has improved. But these aren't the only reasons for the increase. Another important factor was a change made in 1991 in the kind of pertussis vaccine used in the United States. How has the pertussis vaccine changed? The first pertussis vaccine contained inactivated but complete bacterial cells. Typically, vaccines contain bits of the target microbe, which trigger our immune systems to mount a defense against them and—most importantly—remember them in case of future invasion.

The whole cells in the old vaccine offered the immune system a huge selection of pertussis-specific targets to recognize and remember. But then some people became concerned because the vaccine was causing seemingly alarming reactions, including fever-induced seizures and fainting. Even though these reactions didn't cause any lasting damage, the relatively high rate of these reactions (about one in every 1,000 doses of the vaccine resulted in a seizure event) prompted the development and approval of a new version of the pertussis vaccine. Instead of using the whole bacterial cell, it offers the immune system only select bits of the cell that trigger an immune defense. Because it doesn't rely on complete cells, the new version is called an acellular vaccine. Is the newer pertussis vaccine less long-lasting? It turns out that the host of molecules in the whole-cell vaccine probably triggered a stronger and longer-lasting immune response than the newer, acellular vaccine does. Those of an age to have received the newer version exhibit shorter-lasting immunity than those who got the whole-cell vaccine. The numbers are clear: With whole-cell vaccination, cases nationwide stayed in the low four digits for decades. With the advent of the acellular version, the number of U.S.

cases climbed again, reaching almost 50,000 in 2012. Meanwhile, in countries such as Thailand that continued to use the whole-cell vaccine, case numbers have remained low and have even continued to decline. As a result of the waning immunity of the acellular vaccine, U.S. preteens now receive an additional inoculation, at age 11 or 12 years. The first five shots, given from infancy through age four to six years, are in a formulation known as DTaP (for diphtheria, tetanus, and acellular pertussis). The sixth shot, the preteen booster, is referred to as the Tdap—an existing tetanus and diphtheria booster, now with pertussis added in. Is pertussis a moving target? The new version of the pertussis vaccine might have had yet another unanticipated effect: opening the door to changes in the bacteria. Some recent samples of the B. pertussis bacterium from infected people contain cells that no longer make the molecules used in the vaccine to trigger the immune system. Without these recognizable molecules, the altered bacteria can slip right past the immune system's defenses.

The upshot could be that an already relatively weak vaccine is becoming even weaker. What is the role of vaccine refusal? According to the CDC, about 5% of children in the United States have received less than three shots in the DTaP vaccine series. Parental refusal to vaccinate their children against pertussis has been tagged as one factor in the 2010 California outbreak. Regions where more parents requested vaccine exemptions for nonmedical reasons were 2.5 times more likely to also see a high number of pertussis cases. Protecting a community against pertussis requires that at least 92% of the population be immune. Given the complexities of waning immunity, as well as a weaker pertussis vaccine than was previously used in the United States, maintaining that threshold to achieve " herd immunity" is more critical than ever—especially to protect infants, who are the segment of the population most vulnerable to the disease. Emily Willingham is a Northern California-based writer who covers many topics, including vaccines and autism. She has written for the New York Times, Discover, and Forbes and is co-authoring an upcoming book on evidence-based parenting.

Laura Helft is the senior researcher for Tangled Bank Studios, a production company of the Howard Hughes Medical Institute. She produces supporting web content for the science programming produced by Tangled Bank. Related Links

Question: What is the more common name of the disease pertussis?
Answer: Whooping cough